PROJECT SUMMARY/ABSTRACT Acute lung injury (ALI), Acute Respiratory Distress Syndrome (ARDS), and Neonatal Respiratory Distress Syndrome (NRDS) are common, devastating clinical syndromes that affect large numbers of adult and neonatal patients (200,000 cases in the US per year) and have up to 40% mortality with the current standard of care. Our ultimate goal is to develop nonviral gene therapy approaches to treat ALI. We have shown that electroporation can be used to transfer genes to lungs with established lung injury and pulmonary edema to treat the disease and lessen the severity of the injury. The method is simple, fast, and safe. In order to move this toward clinical application, we must demonstrate its efficacy and safety in a large animal model that represents the human disease and develop the most simple and safe method possible in order for it to be accepted by clinicians. The highest recommendation for an animal model is good evidence that the results of the study would be similar in a clinical trial To this end, we have recently applied this approach to a group pigs (35-40 kg) using energies less than 0.1 J/kg and have achieved gene transfer to the lungs with no mortality or injury. Our R21 Phase specific aims are to (1) optimize electroporation parameters for safety and gene transfer to the lungs of pigs, (2) evaluate methods of DNA delivery, (3) develop and optimize a bronchoscope-based electrode for lung gene delivery, and (4) determine whether gene transfer of ENaC as well as Na,K-ATPase subunit genes increases efficacy of gene therapy for treatment of lung injury in a mouse model. At the end of the R21 phase, we will have established optimal parameters for gene delivery to the pig lung and have determined the best therapeutic gene combination to treat lung injury in two complementary pig models of ALI. The R33 phase specific aims are (1) evaluate efficacy of electroporation-mediated gene transfer of Na,K-ATPase/ENaC gene subunits to prevent lung injury in a saline lavage model of mild-moderate ALI, (2) determine whethere transfer of these genes can treat pre-existing lung injury in this model, (3) determine whether transfer of these genes can protect from lung injury in a severe sepsis-induced cecal ligation and pucture model of ARDS, and (4) evaluate whether this approach can be used to treat previously established sepsis-induced lung injury in this model. These studies will provide us with the proof-of-principle for transthoracic pulmonary electroporation and establish the safety and efficacy in an two established pre-clinical models. PROJECT NARRATIVE Acute lung injury, Acute Respiratory Distress Syndrome (ARDS), and Neonatal Respiratory Distress Syndrome are common, devastating clinical syndromes that affect an estimated 200,000 adult and neonatal patients each year in the US and have up to 40% mortality with the current standard of care. We have developed a nonviral gene therapy approach using electric fields that can prevent as well as treat existing ARDS in two small animal models. The work proposed in this study will extend these findings to a large animal model to evaluate whether these findings can be translated into larger subjects and ultimately humans. At the end of the study, we will have demonstrated efficacy of this novel approach to treat lung injury in an established pre-clinical model.